I wanted to make one suggestion, instead of having a pure Regular Expression break it apart and assign it to variables to make it more readable.

use strict;
use warnings;

my $IP_ADDRESS = qr{(?:\d{1,3}\.){3}\d{1,3}}xms;
my $HOST_NAME  = qr{\S*}xms;

my $HN = 'fred';

while (<DATA>) {
    next if ! qr{\A ($IP_ADDRESS) \s+ ($HOST_NAME) }xms;
    next if $HN ne $2;
    print "$1\n";
    print "$2\n";
}

__DATA__
0.0.0.22    fred localhost
0.0.63.23    fred-test-0
1.0.128.24    fred-test-1
[download]